Study: Universe could end in 10 billion years

(CNN) --Stanford University researchers theorize that the universe could experience a cosmic crunch in 10 billion or 20 billion years.

Recent cosmological observations have suggested that the universe will expand at an increasingly rapid rate for at least 100 billion years and perhaps enlarge forever.

But according to a new scientific model, the universe will slow its pace of acceleration and then experience a fatal contraction.

"The universe may be doomed to collapse and disappear. Everything we see now, and at a much larger distance that we cannot see, will collapse into a point smaller than a proton," said Andrei Linde, who conducted the research with Renata Kallosh, his wife and physics colleague at Stanford.

"The standard vision at the moment is that the universe is speeding up, so we were surprised to find that a collapse could happen with such a short amount of time," Linde said.

Linde is one of the pioneers of Inflation theory, an increasingly popular revision of the proposed Big Bang.

First advanced in the 1980s, it suggests that the universe rapidly inflated into a much larger cosmos only a fraction of a moment after it began.

Will the universe expand forever and become cool and dark, collapse into nothingness in a cosmic crunch, or remain in equilibrium between the forces of gravity and expansion?

Inflationary theory predicts a "flat" universe, or one where the competing forces pulling and contracting the universe stay balanced.

The debate, by no means settled among cosmologists, hinges on the role of mysterious and theoretical phenomena known as dark matter and dark energy.

Throw into the mix such notions as string theory, supergravity, extra dimensions and multiple universes, and the question becomes even more muddled.

Yet looking at some of the best work in the field of dark energy, Linde and Kallosh concluded it would change from a positive to a negative force.

Their cosmological model, described in related reports on www.arXiv.org, a Web site sponsored by the National Science Foundation and Cornell University, generated another unexpected prediction: the universe, estimated to be about 14 billion years old, is already middle-aged.

"Physicists have known that dark energy could become negative and the universe could collapse sometime in the distant future, perhaps a trillion years," Linde said. "But now we see that we might be not in the beginning, but in the middle of the life cycle of our universe."

One noted scientist had a lukewarm response to the hypothesis.

"Because their proposal is based on rather specific models and assumptions and their is no current evidence for it, I would say it logically possible, but not compelling," said physicist Paul Steinhardt.

The Princeton University professor helped developed an alternative cosmological theory that proposes that the universe began by colliding with another universe, with both existing in a higher dimensional medium.

"They are only attempting to explain the evolution of the universe between now and the collapse, whereas we showed how this can be embedded in a larger cyclic scenario that leads to an eternal universe," Steinhardt said.

Linde concedes that the work is raw and that astronomy is an inexact science at best, and known for continuous revisions. Recalling an ongoing joke among cosmologists, the Stanford University professor quipped: